1. Field of the Invention
This invention relates to a method for driving a head-seek stepping motor of a disk drive device for recording or reproducing information, which is arranged to perform a head seek action by moving recording/reproducing heads over a disk-shaped recording medium in the radial direction of the disk-shaped recording medium.
2. Description of the Related Art
A floppy disk drive device (hereinafter referred to as FDD) is known as a typical disk drive device of the above-stated kind. The FDD is arranged as described in outline below with reference to FIG. 1
In FIG. 1, reference numeral 1 denotes a flexible magnetic disk called a floppy disk (a disk-shaped magnetic recording medium). The magnetic disk 1 is mounted on a spindle 2 and is driven to rotate by a disk driving motor 3. Magnetic heads 4a and 4b are transducers which are mounted on a carriage 5 and arranged to be in pressed contact with both surfaces of the magnetic disk 1 for recording and reproduction of information on and from the magnetic disk 1. The carriage 5 is movable in the directions of arrows "a" and "b" along the radial direction of the magnetic disk 1. The magnetic heads 4a and 4b are thus arranged to be movable toward both the inner and outer circumferences of the magnetic disk 1 for a so-called head seek, which hereinafter means positioning a head at a designated track position on a magnetic disk. The carriage 5 is arranged to be driven by a stepping motor 6 through a head seek mechanism which is not shown but consists of a lead screw, a steel belt, etc.
In performing a recording or reproducing action, the magnetic disk 1 is driven to rotate by the disk driving motor 3 under the control of a control circuit which is not shown. Meanwhile, the carriage 5 is driven by the stepping motor 6 to move in the direction of arrow "a" or "b". The magnetic heads 4a and 4b are thus moved to a desired track position on the magnetic disk 1. The recording or reproduction is then performed in or from the track on the magnetic disk 1.
The conventional method of driving the stepping motor 6 for the head seek of the above-stated FDD is described with reference to FIG. 2 as follows In FIG. 2, reference numeral 11 denotes a step signal which comes from a host system to give an instruction by one pulse at a time for one step driving of the stepping motor 6. Reference numerals 12 to 15 denote exciting signals for exciting the coil of the stepping motor 6 respectively in its phases .phi.A to .phi.D. The exciting signals 12 to 15 are in their excitied states when they are at high levels.
According to the conventional method, the phase transition of the stepping motor 6 is effected in response to the pulses S1 to S6 of the step signal 11 from the host system as shown in FIG. 2. An excited state is held unvaried throughout a period between one pulse of the step signal and arrival of a next pulse of the step signal. After the last (step) pulse S6, the coil of the stepping motor is excited for a certain given period, and, then, there is obtained a non-excited state, or a holding state.
However, since the excited state is maintained during the period from one pulse until arrival of a next pulse of the step signal, seeking is apt to be performed with an unnecessarily large power. This tendency becomes strong especially in cases where the step intervals are long (a slow seek speed). Therefore, the conventional method not only increases the power consumption of the stepping motor but also makes the sound of the seek large to increase the noise of operation.